Iron, as an important nutritional element, is essential to human body. The deficiency or poor availability of iron might lead to disorders of metabolic processes such as transportation and storage of oxygen, transportation of carbon dioxide as well as oxidations and reductions, influence growth and development, and even lead to various diseases such as anemia; and iron deficiency anemia (IDA) will occur if the storage or intake of iron is insufficient. IDA refers to anemia which occurs when storage iron in the body available for producing hemoglobin has been depleted and erythropoiesis disorder develops. It is one of nutritional deficiency diseases with the highest incidence rate, and is common in children, pregnant and lactating women as well as patients with chronic diseases. According to a report from WHO (World Health Organization), about 10%-30% of the populations in the world suffer from iron deficiency at different levels, wherein the incidence rate is about 10% in male and >20% in female. An investigation shows that there are up to 38 million people suffering from anemia at different levels in China.
Nowadays, the prevention and treatment of iron deficiency anemia is mainly effected by iron supplementing agents. Conventional iron supplement agents include ferrous sulfate, ferrous chloride, ferrous gluconate, ferrous lactate, ferrous succinate, ferrous fumarate, etc. Although these iron supplement agents have high iron contents and good iron supplementing effects, they have a special rusty taste and are not suitable for long term consumption. In addition, they have low availability in human body and have significant adverse effects (various symptoms are prone to occur, e.g. bad smell, nausea, bloating, disorders of digestive organs, diarrhea, and constipation). Further, ferrous iron is unstable in gastrointestinal tract, and is prone to oxidation into ferric iron. Iron contained in heme of hemoglobin is in the form of ferrous iron, which will thus lead to low availability thereof in human body.
Ferroporphyrin (Porphyrin iron) belongs to natural substances, and is conventionally extracted from pig blood. It is a main component of erythrocytes and thus is also known as “heme”. It is an iron porphyrin complex consisting of porphyrin and one molecular unit of ferrous iron. Porphyrin iron, known as a superior iron supplementing product, is free from being influenced by phosphoric acid, carbonic acid, tannic acid, oxalic acid, phytic acid, etc. and can be absorbed into blood directly by intestinal mucosa. Its bioavailability is lightly higher than conventional iron supplementing agents.

Although it has good iron supplementing effects, porphyrin iron has a special blood smell and consequently a poor taste, since it is extracted from pig blood. In addition, porphyrin iron is structurally unstable and prone to oxidation, and it also has an irritating effect on the digestive tract, e.g. stomach burning, nausea, etc., resulting in poor patient compliance to administration. Porphyrin iron is soluble in sodium hydroxide solution, hot alcohols or ammonia and slightly soluble in hot pyridine, but insoluble in water, diluted acids, ethers, chloroform, etc. Its absorption in gastrointestinal tract is limited by its relatively poor water solubility. According to a report by Zhao Di (Absorption Of 58Iron Originating From Hemin In Rat Using Extrinsically Label Method, Chinese Journal of Clinical Pharmacology and Therapeutics, 2012, 17(6): 639-643), the absolute oral bioavailability of porphyrin iron in rats is only 0.93%. On the other hand, porphyrin iron has an extremely low iron content in heme. As shown in the above structure, 6 rings of porphyrin are complexed with an iron atom, and thus during the absorption process, the ferrous ion can be released only after the 6 rings of porphyrin are destroyed. Therefore, in order to improve iron supplementing effects, the dosage of porphyrin iron should generally be increased. However, the increase in dosage will decrease the patient compliance to administration, leading to poor iron supplementing effects. Therefore, such disadvantages largely limit the development and application of porphyrin iron in foods and health products.
Most of current commercial porphyrin iron products are conventional porphyrin iron capsules without significant improvements in terms of the blood smell and irritations to digestive tract. In addition, oral porphyrin iron solution has been developed, to which casein phosphopeptides (CPP) for improving iron adsorption and Vitamins are added. This product not only fails to ameliorate the blood smell and digestive tract irritations or improve bioavailability of porphyrin iron, but also limits the application thereof, since CPP induces allergic responses in patients allergic to milk or seafoods due to the allergenicity of CPP.
Many patents and literatures relating to porphyrin iron have been disclosed and published, most of them focus on the extraction and preparation thereof, but few focus on ameliorating its blood smell or reducing its digestive tract irritations.
CN101254207A discloses a liposome preparation comprising porphyrin iron and/or inorganic iron, and preparation process thereof, wherein a liposome comprising porphyrin iron and/or inorganic iron, cholesterol and lecithin is prepared by utilizing a rotary thin film-ultrasonic process. The liposome preparation improves stability and bioavailability of porphyrin iron. However, the porphyrin iron liposome prepared by the process has an encapsulation rate of only 30-36%, and the lecithin in the preparation is prone to oxidation and is of high cost. In addition, the liposome per se has poor physical stability, which is unfavorable for storage and transportation and makes industrial production thereof difficult.
CN102726738A discloses an oil suspension type soft capsule with iron supplementing function, comprising iron materials (porphyrin iron/ferrous fumarate), Vitamin C, casein phosphopeptides, soybean oil, folic acid, beeswax, and gelatin capsule shells. Although the soft capsule can mask some of the blood smell and the Vitamin C and casein phosphopeptides added can improve the adsorption of iron in human body, Vitamin C per se is unstable and is prone to oxidation. Furthermore, there is a risk that CPP may induce allergies in patients allergic to milk or seafoods. Also, the soft capsule per se has a significant stability problem, i.e., the component of the capsule shell, gelatin, is prone to aging due to crosslinking reaction, resulting in a change in dissolubility of the capsule shell and thereby influencing the disintegration rate of the soft capsule. Furthermore, propylene glycol and sorbitol used in the capsule shell are prone to oxidation during storage, forming some low molecular weight aldehydes, thereby accelerating the crosslinking reaction of gelatin and in turn delaying the disintegration of the soft capsule.
Therefore, there is still a need for a porphyrin iron preparation which can not only overcome the disadvantages of porphyrin iron per se but also incorporate some stable, low cost and non-allergic adjuvants. In the meantime, it is desired to obtain a porphyrin iron composition with ameliorated digestive tract irritations and improved mouthfeel, bioavailability and/or stability by a simple and easy-operable formulation process.